1. Field of the Invention
The present invention relates to a valve connector to be used, for example, for controlling a fuel evaporating gas (vapor) in piping such as evaporation piping or vapor return piping in a fuel supply system of a motor vehicle.
2. Description of the Related Art
In order to prevent fuel vapor gas generated in a fuel tank of a motor vehicle from being discharged into an atmosphere, a vapor discharge prevention mechanism that causes the vapor to be adsorbed in a canister has been widely employed. In this type of vapor discharge prevention mechanism, evaporation piping connecting a fuel tank and the canister uses a one-way valve or a check valve to maintain an appropriate pressure in the fuel tank by controlling a flow of the vapor. And, in the vapor discharge prevention mechanism, around a mouth of an inlet pipe and the fuel tank is connected by means of vapor return piping, a part of the vapor in the fuel tank is introduced to the mouth of the inlet pipe via the vapor return piping, and it is prevented that an external air is caught up in the mouth of the inlet pipe at fuel supply from outside. Thereby generation of the vapor is restrained. There is provided the one-way valve or the check valve in a middle portion of the vapor return piping for controlling a flow of the vapor according to an internal pressure of the fuel tank.
In this type of the evaporation piping or the vapor return piping, a rubber hose is connected to each end of the one-way valve or the check valve. And, an end portion of one rubber hose is connected to, for example, a connecting pipe on a side of a roll-over valve or a differential pressure regulating valve disposed on the fuel tank. Also, an end portion of the other rubber hose is connected to a connecting pipe on a side of the canister or a connecting pipe on a side of the inlet pipe. However, as there is a tendency to restrict strictly transpiration of a fuel from a fuel supply system, a resin tube is also used instead of the rubber hose. When the resin tube is used, in many cases, the resin tube is connected to the connecting pipe by means of a connector or a quick connector. And, under the increasing demand for low fuel transpiration in recent years, minute fuel transpiration from a connecting region between the rubber hose or the resin tube and the one-way valve, etc. cannot be ignored. So, there is a need to reduce the number of connecting regions between structural elements to lower fuel transpiration.
Accordingly, it is proposed that the one-way valve or the check valve is equipped or added in a quick connector, for example, having an inserting portion for the connecting pipe. Thereby the parts count itself, i.e. the number of parts in the evaporation piping, the vapor return piping or the like, and the number of the connecting regions between the structural elements are reduced to achieve low fuel transpiration.
A known type of quick connector, in which a one-way valve or check valve is equipped or added, comprises, for example, a connector housing that has a tube connecting portion on one axial end thereof and a pipe inserting portion on the other axial end thereof, a valve seat surface that is defined in an inner surface of the connector housing near the tube connecting portion, a valve body that is disposed in the connector housing so as to move toward and away from the valve seat surface in an axial direction, and a compression spring that is mounted in the connector housing for biasing the valve body toward the valve seat surface. Such type of quick connector is disclosed, for example, in Patent Document 1. The valve body closes the fluid flow path by abutting an abutting surface defined on an outer peripheral portion of a closing portion with the valve seat surface. The fluid flow path is opened when the valve body is subject to a fluid pressure from the one axial end and moves in a direction away from the valve seat surface.
[Patent Document 1] JP-A, 2004-116733
Meanwhile, in this type of valve connector disclosed in Patent Document 1, when a valve body is moved in an axial direction by fluid pressure change, a valve body may move while rotating with respect to a connector housing, for example, at high speed, depending on how a fluid pressure acts on the valve body. Then, responsiveness of the valve body to the fluid pressure is affected depending on how the valve body (for example, a guide) slides rotationally with respect to the connector housing, resulting in unstable pressure-flow characteristics of the valve connector. Also, the compression spring is disposed on the other axial end with respect to the valve body with one axial end portion thereof supported at the valve body. In a supporting structure of the one axial end portion of the compression spring, the one axial end portion of the compression spring is fitted in a support recess formed in each of a plurality of the guides of the valve body. So, when shock is given to the valve connector by drop of the valve connector, etc. before the valve connector is installed in a piping, or shock or the like is given by vehicle vibration, etc. after the valve connector is installed, the valve body is impulsively moved in a circumferential direction and an axial direction, there is a fear that a part of the one axial end portion of the compression spring is ejected out of the support recess of the guide, for example, so as to engage with the other axial extreme end or edge of the guide. Then, spring characteristics of the compression spring is changed, and it is no longer possible to expect desired operation of the valve connector.
Under the circumstances described above, it is an object of the present invention to provide a valve connector that can maintain, stable operating characteristics.